Abstract: In order to solve the problems of non-comprehensive consideration of factors and low calculation accuracy of existing calculation models for layered water injection allocation, a coupling model featuring wellbore pipe flow, nozzle orifice flow, and formation seepage was established, to calculate the layered water injection volume. Meanwhile, an inversion calculation method for the nozzle allocation of layered water distributors was established by considering the constraints of wellhead pressure and formation pressure. In addition, the forward and inverse calculation results of the model under different conditions were discussed. The results indicated that the established model could accurately calculate the injection volume and pressure of each water injection layer at different times. The diameter of the single-layer water distributor’s nozzle was positively correlated with the injection volume of the layer and inversely correlated with the injection volume of other layers. The established model could give an optimal nozzle allocation scheme while meeting the pressure constraint conditions, provide a more accurate injection volume calculation and nozzle allocation method of water distributors for layered water injection technology, and guide on-site layered water injection allocation.